JP2009270039A - Water absorptive crosslinked polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water absorptive resin that is high in impact resistance and does not show any marked decrease in its liquid transparency caused by an impact such as collisions etc. during carriage or transportation of the water absorptive resin, and that has an excellent water absorption property against an aqueous liquid or body fluids such as urine, menstrual blood or sweat, and to provide a method for producing the same. <P>SOLUTION: The water absorptive crosslinked polymer includes a crosslinked polymer (A) obtained by polymerization of monomer components containing a water-soluble monomer and at least one sort of silicon compound (B) selected from an alkoxy silane represented by formula (1), a hydrolyzed product thereof, and their polycondensation products, provided that formula (1) is R<SP>1</SP><SB>p</SB>Si(OR<SP>2</SP>)<SB>4-p</SB>, wherein, R<SP>1</SP>and R<SP>2</SP>are a 1-6C alkyl group or 2-6C alkenyl group, and p is an integer of 0-3. The method for producing the same is performed accordingly. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water-absorbing crosslinked polymer having excellent impact resistance, water absorption and liquid permeability, and a method for producing the same, and more specifically, water absorption performance resulting from impact such as collision caused by transportation / transport of the crosslinked polymer. The present invention relates to a water-absorbent crosslinked polymer having good water-absorbing performance with respect to an aqueous liquid or a body fluid such as urine, menstrual blood or sweat without undergoing a significant decrease, and a method for producing the same.

  Superabsorbent resin is used in hygiene products such as disposable diapers for infants, adults and incontinents, and absorbent articles such as sanitary napkins for women, water retention agents in agricultural and horticultural fields, etc. Widely used as agents, anti-condensation agents, water-stopping agents, etc.

  In recent years, with the thinning of sanitary goods, the ratio of the water-absorbing resin in the absorbent body tends to increase. The water-absorbent resin used in the sanitary products field is responsible for (1) the ability of the water-absorbent resin to absorb and retain the original body fluid (a large amount of water absorption) and (2) the fibers (pulp, etc.) in the absorber. The ability to diffuse body fluids (high fluid flow rate) is required. In order to satisfy (1) and (2), it is necessary to precisely control the shape of the water-absorbent resin (the size of the particles and the degree of unevenness) and the cross-linking density. Many patent documents have been filed (see, for example, Patent Documents 1 to 3).

Patent Document 4 discloses that XRSiY _n (X is a group capable of reacting with a functional group of a polymer, R is an organic group, Y is a hydrolyzable group, and n is an integer of 1 to 3). A superabsorbent polymer obtained by adding a silane coupling agent represented by the formula:

However, these conventional water-absorbing resins have a problem that the resin particles are crushed by an impact such as a collision during transportation and transportation of the resin, and the liquid passing speed is remarkably reduced.
JP 2001-258933 A JP 2001-252307 A Japanese National Publication No. 9-510889 JP-A-61-211305

  The problem of the present invention is that it has good impact resistance without undergoing a significant decrease in the flow rate due to impact such as collision caused by transport / transport of the water-absorbent resin, such as aqueous liquid, urine, menstrual blood or sweat. An object of the present invention is to provide a water-absorbing resin having a good water-absorbing performance for body fluids and the like and a method for producing the same.

The present invention relates to a crosslinked polymer (A) obtained by polymerizing a monomer component containing a water-soluble monomer, and a general formula (1).
R ¹ _p Si (OR ² ) _4-p (1)
[Wherein, R ¹ and R ² each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms or a linear or branched alkenyl group having 2 to 6 carbon atoms, and p R ¹ and (4-p) R ² may be the same or different. p shows the integer of 0-3. ]
A water-absorbing crosslinked polymer containing at least one silicon compound (B) selected from alkoxysilanes (hereinafter referred to as alkoxysilanes (1)), hydrolysates thereof and polycondensates thereof, and A manufacturing method is provided.

  The water-absorbing crosslinked polymer of the present invention has good impact resistance without lowering the liquid passing speed even when subjected to impacts such as collisions caused by transportation and transportation. For example, the absorbent in hygiene products such as diapers and sanitary products Can be used to absorb body fluid quickly, can diffuse body fluid over a wider range, and can retain body fluid absorbed by the absorber, and uses the water-absorbent crosslinked polymer of the present invention. Thus, the sanitary product can be thinned.

[Crosslinked polymer (A)]
The crosslinked polymer (A) used in the present invention is a crosslinked polymer obtained by polymerizing a monomer component containing a water-soluble monomer.

  The water-soluble monomer used when producing the crosslinked polymer (A) is a water-soluble monomer having a polymerizable unsaturated group. Specifically, olefinic unsaturated carboxylic acid or salt thereof, olefinic unsaturated carboxylic acid ester, olefinic unsaturated sulfonic acid or salt thereof, olefinic unsaturated phosphoric acid or salt thereof, olefinic unsaturated phosphate ester And vinyl monomers having a polymerizable unsaturated group such as olefinically unsaturated amine, olefinically unsaturated ammonium, and olefinically unsaturated amide.

  Examples of the olefinic unsaturated carboxylic acid or a salt thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid, alkali metal salts and ammonium salts thereof. Examples of olefinic unsaturated carboxylic acid esters include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, and phenoxypolyethylene glycol (meth). An acrylate etc. are mentioned.

  Examples of the olefinic unsaturated sulfonic acid or a salt thereof include vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, 2- (meth) acryloylethane sulfonic acid, 2- (Meth) acryloylpropanesulfonic acid or a salt thereof can be used. Examples of the olefinic unsaturated phosphoric acid or a salt thereof include (meth) acryloyl (poly) oxyethylene phosphoric acid ester or a salt thereof.

  Examples of the olefinic unsaturated amine include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and N, N-dimethylaminopropyl. (Meth) acrylamide etc. are mentioned. Examples of the olefinic unsaturated ammonium salt include quaternary ammonium salts of the above olefinic unsaturated amines, and examples of the olefinic unsaturated amide include (meth) acrylamide, methyl (meth) acrylamide, and N-ethyl (meth). Examples include (meth) acrylamide derivatives such as acrylamide, N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, and vinylmethylacetamide.

Specific examples of the other monomer include nonionic hydrophilic group-containing unsaturated monomers such as vinylpyridine, N-vinylpyrrolidone, N-acryloylpiperidine, N-acryloylpyrrolidine, and N-vinylacetamide.
These monomers can be used alone or as a mixture of two or more.

  In the present specification, (meth) acrylate means acrylate or methacrylate, (meth) acrylamide means acrylamide or methacrylamide, and (meth) acryloyl means acryloyl or methacryloyl.

  Among these monomers, olefinic unsaturated carboxylic acids or salts thereof are preferred, acrylic acid, methacrylic acid, alkali metal salts, alkaline earth metal salts or ammonium salts thereof are more preferred, acrylic acid, alkali metal acrylate salts. (Sodium salt, potassium salt, etc.) and ammonium acrylate are more preferable.

  When the monomer is solid at room temperature, it can be used as an aqueous solution. At this time, the concentration of the monomer in the aqueous solution is preferably 10% by weight or more, more preferably 20% by weight or more, and still more preferably 30% by weight or more from the viewpoint of productivity.

  The water-soluble monomer can be used in combination with a water-insoluble monomer that can be copolymerized therewith. Examples of the water-insoluble monomer include unsaturated carboxylic acid esters such as acrylic acid, methacrylic acid, maleic acid and fumaric acid having an alkyl group having 1 to 18 carbon atoms, and styrene. In this case, the content of the water-soluble monomer is preferably 50% by weight or more, particularly preferably 70% by weight or more in the total monomers.

  In the polymerization of monomers, it is preferable to use an inert hydrophobic organic solvent. Examples of the hydrophobic organic solvent inert to the polymerization include aliphatic hydrocarbons such as n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane and methylcyclohexane; aromatic hydrocarbons such as benzene and toluene; n- Examples thereof include aliphatic alcohols having 4 to 6 carbon atoms such as butyl alcohol and n-amyl alcohol; aliphatic ketones such as methyl ethyl ketone; aliphatic esters such as ethyl acetate; silicone oils; Among these hydrophobic organic solvents, linear or cyclic aliphatic hydrocarbons having 6 to 12 carbon atoms are preferable. The hydrophobic organic solvent can be used as one kind or a mixture of two or more kinds. The amount of the hydrophobic organic solvent to be used is preferably 50 to 500 parts by weight, more preferably 100 to 500 parts by weight with respect to 100 parts by weight of the monomer or an aqueous solution thereof.

  In addition to the hydrophobic organic solvent, an amphiphilic organic solvent may be used. Specific examples of the amphiphilic organic solvent include alcohols such as methanol, ethanol, propanol and 2-propanol; ketones such as acetone; ethers such as tetrahydrofuran and dioxane. The amount of the amphiphilic organic solvent used is the total amount with the hydrophobic organic solvent and is preferably up to 500 parts by weight with respect to 100 parts by weight of the monomer.

  Moreover, it is preferable to use a dispersing agent in the polymerization of the monomer, and the dispersing agent is preferably an anionic surfactant.

As an anionic surfactant, N-acyl (acyl group having 6 to 30 carbon atoms) aspartic acid or a salt thereof, N-acyl (acyl group having 6 to 30 carbon atoms) glutamic acid or a salt thereof, acylation (acyl group) Of carbon number 5 to 30) taurine or a salt thereof, or the formula (I)
RO (A) _m XO ₃ M (I)
(In the formula, R represents a linear or branched alkyl group or alkenyl group having 6 to 22 carbon atoms, or an aryl group having 12 to 28 carbon atoms in total, and A represents a linear or branched alkylene group. Or an oxyalkylene group, m represents an average value of 0 to 22, X represents S or P, and M represents a cation or a hydrogen atom.)
The compound represented by these is mentioned.

  Examples of N-acyl aspartic acid or a salt thereof include N-palmitoyl aspartic acid monosodium salt, N-palmitoyl aspartic acid disodium salt, N-palmitoyl aspartic acid and the like. N-acyl glutamic acid or a salt thereof includes N-myristoyl glutamic acid monosodium salt, N-lauroyl glutamic acid monosodium salt, N-stearoyl glutamic acid monosodium salt, N-myristoyl glutamic acid monosodium salt, N-coconut oil fatty acid acyl glutamic acid Examples thereof include monosodium salt, N-cured tallow fatty acid acyl glutamic acid monosodium salt, N-stearoylglutamic acid, N-stearoylglutamic acid monopotassium salt and the like. The acylated taurine or a salt thereof is preferably an acylated taurine having 10 to 18 carbon atoms of an acyl group or an alkali metal salt thereof.

  In the compound represented by the formula (I), R is an alkyl having 10 to 18 carbon atoms such as 6 to 22, more preferably 8 to 20, especially decyl group, lauryl group, myristyl group, palmityl group, stearyl group, etc. Groups are preferred. As the cation represented by M, alkali metal ions and ammonium ions are preferable, alkali metal ions are more preferable, and sodium ions and potassium ions are still more preferable.

  As the compound represented by the formula (I), polyoxyalkylene (the number of carbon atoms of the alkylene group is 2 to 3, the average number of added moles of the oxyalkylene group is 0 to 22) alkyl or alkenyl (the number of carbon atoms of the alkyl group or alkenyl group) 6-22) Ether sulfate or a salt thereof is preferable, and polyoxyethylene alkyl (alkyl group having 12 to 18 carbon atoms) ether sulfate or an alkali metal salt thereof is more preferable.

  In the present invention, in addition to the anionic surfactant, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant, or a polymer type dispersant can be used in combination.

These surfactants or polymeric dispersants include sorbitan fatty acid esters such as sorbitan monostearate, sorbitan monolaurate and polyoxymethylene sorbitan monooleate; glycoside compounds such as alkyl glucosides; celluloses such as ethyl cellulose and benzyl cellulose Ethers; cellulose esters such as cellulose acetate, cellulose butyrate and cellulose acetate butyrate; cationic and amphoteric surfactants such as trimethylstearyl ammonium chloride and carboxymethyldimethylcetylammonium; maleated polybutadiene, maleated polyethylene, styrene -Dimethylaminoethyl methacrylate quaternary salt copolymer and isopropyl methacrylate-dimethylaminoethyl methacrylate The polymer dispersing agent such as 4 Kyushiotomo polymer can be exemplified.
These dispersants can be used alone or in combination of two or more.

  The amount of the dispersant used is preferably 0.01 to 25 parts by weight, more preferably 0.01 to 5 parts by weight, and still more preferably 0.01 to 2.5 parts by weight with respect to 100 parts by weight of the monomer. .

  In the polymerization of the monomer, it is preferable to use a polymerization initiator. The polymerization initiator is not particularly limited, and an oxidizing polymerization initiator, an azo polymerization initiator, a redox polymerization initiator, and the like can be used.

  Examples of the oxidative polymerization initiator include ketone peroxides such as methyl ethyl ketone peroxide and methyl isobutyl ketone peroxide; dialkyl peroxides such as di-tert-butyl peroxide and tert-butyl cumyl peroxide; tert-butyl peracetate Alkyl peresters such as tert-butyl perisobutyrate and tret-butyl pivalate; hydroperoxides such as tert-butyl hydroperoxide, cumene hydroperoxide and hydrogen peroxide; potassium persulfate, sodium persulfate, persulfate Persulfates such as ammonium; perchloric acids such as potassium perchlorate and sodium perchlorate; and halogenates such as potassium chlorate and potassium bromate.

  Examples of the azo polymerization initiator include 2- (carbamoylazo) -isobutyronitrile, 2,2′-azobis (N, N′-dimethyleneisobutylamidine) dihydrohalide, 2,2′-azobis (2-amidino). Propane) dihydrohalide, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrohalide, 2,2'-azobis (N, N'-dimethyleneisobutylamidine), 4,4 ' -Azobis (4-cyanopentanoic acid), 4,4'-azobis-4-cyanovaleric acid, azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2,4-dimethylvalero) Nitrile), (1-phenylethyl) azodiphenylmethane, dimethyl-2,2′-azobisisobutyrate, 2,2′-azobis (2 Methylbutyronitrile), 1,1′-azobis (1-cyclohexanecarbonitrile), 2,2′-azobis (2,4,4′-trimethylpentane), 2-phenylazo-2,4-dimethyl-4- Examples thereof include methoxyvaleronitrile and 2,2′-azobis (2-methylpropane). In the above compound, the halide is preferably chloride from the economical viewpoint.

  Examples of the redox polymerization initiator include hydrogen peroxide / ferrous salt, persulfate / sulfite, cumene hydroperoxide / ferrous salt, hydrogen peroxide / L-ascorbic acid, and the like.

  When using the polymerization initiator, one or more kinds can be used, and an oxidizing polymerization initiator, an azo polymerization initiator, and a redox polymerization initiator may be used in combination.

  Among these, from the viewpoint of achieving the object of the present invention, potassium persulfate, sodium persulfate, 2,2′-azobis (2-amidinopropane) dihydrohalide and 2,2′-azobis [2- (2-imidazoline) One or more selected from the group comprising -2-yl) propane] dihydrohalide is preferred.

  The amount of the polymerization initiator used is usually preferably 0.001 to 10% by weight, more preferably 0.01 to 5% by weight, based on the monomer. The method for adding the polymerization initiator is not particularly limited, but it is preferably added to the polymerization solvent and / or to the monomer. Further, it is preferable to use an azo polymerization initiator at the beginning of the reaction and a persulfuric acid polymerization initiator at the latter half of the reaction.

  Moreover, as a method for introducing a crosslinked structure into the crosslinked polymer (A), a method of introducing by a self-crosslinking without using a crosslinking agent, two or more polymerizable unsaturated groups and / or two or more in one molecule. Examples thereof include a method of introducing a crosslinking agent having a reactive group by copolymerization or reaction. Only one type of crosslinking agent may be used, or two or more types may be used. Among them, it is preferable to use a compound having two or more reactive groups as a crosslinking agent from the viewpoint of water absorption characteristics of the obtained crosslinked polymer, and further, in combination with a polyvalent ion that acts on an ionic group in the crosslinked polymer. Are preferably used.

  The crosslinking agent can be added before polymerization, at the time of polymerization, and / or after polymerization. Add a cross-linking agent by mixing with an aqueous monomer solution in the polymerization stage, mixing in the reaction system in the polymerization stage, or adding the polymer obtained by polymerization as a solid, aqueous solution or dispersion. Can be used. A crosslinking structure can be constructed in the polymer or on the polymer surface by the crosslinking agent.

  Examples of the crosslinking agent include N, N-diallylacrylamide, diallylamine, triallylamine, diallylmethacrylamide, diallyl phthalate, diallyl malate, diallyl terephthalate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, tetraallyloxy. Polyallyl compounds such as ethane, pentaerythritol triallyl ether, poly (meth) allyloxyalkane; divinylbenzene, N, N′-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol Di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate, glycerin tri (meth) acrylate Polyvinyl compounds such as glycerin acrylate methacrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol Polyglycidyl ethers such as diglycidyl ether and polyglycerin polyglycidyl ether; haloepoxy compounds such as epichlorohydrin, epibromhydrin and α-methylepichlorohydrin; polyaldehydes such as glutaraldehyde and glyoxal; polyvinyl alcohol, Polyols such as polyether-modified silicone; ethylenediamine, diethylenetriamine, trie Polyamines such as tylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, polyvinylpyrrolidone, amino-modified silicone; glycidyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate Hydroxyl vinyl compounds such as 2,4-tolylene diisocyanate, hexamethylene diisocyanate and other polyvalent isocyanate compounds; 1,2-ethylenebisoxazoline and other polyvalent oxazoline compounds; urea, thiourea, guanidine, dicyandiamide, 2-oxazolidinone Carbonic acid derivatives such as 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3-dioxolane 2-one, 4,4-dimethyl-1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1 , 3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one, 1,3-dioxopan-2-one, etc. Alkylene carbonate compounds; polyvalent metal compounds composed of cations such as calcium, magnesium, zinc, aluminum, iron, zirconium, titanium (inorganic or organic metal salts such as hydroxide or chloride); ethylene glycol, diethylene glycol, propylene Glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3-propanediol, dipro Lenglycol, 2,2,4-trimethyl-1,3-pentanediol, polypropylene glycol, glycerin, polyglycerin, 2-butene-1,4-diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,2-cyclohexanol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block Examples include polymers, polyhydric alcohol compounds such as pentaerythritol and sorbitol.

  Among these crosslinking agents, polyvalent metal compounds such as titanium citrate and calcium chloride; polyglycidyl ethers such as ethylene glycol diglycidyl ether and polyglycerin polyglycidyl ether; (poly) ethylene glycol di (meth) acrylate and the like Polyvinyl compounds are preferred.

  The amount of the crosslinking agent having two or more polymerizable unsaturated groups or the crosslinking agent having two or more reactive groups can be any amount according to the desired performance of the final product polymer. The amount is preferably 0.001 to 20% by weight, more preferably 0.01 to 1% by weight based on the total monomers (monomers other than the crosslinking agent having two or more polymerizable unsaturated groups).

  When using a crosslinking agent or an aqueous solution thereof, a hydrophilic organic solvent, an acid or a pH buffering agent may be mixed and used.

  As a method of polymerizing the monomer, the monomer or an aqueous solution thereof and a solvent containing a hydrophobic organic solvent are mixed together and then polymerized (collective polymerization method). The monomer or the aqueous solution thereof contains a hydrophobic organic solvent. A method of sequential polymerization while dropping into a solvent (sequential polymerization method), a mixed solution obtained by mixing or dispersing a monomer or an aqueous solution thereof with a solvent containing a part of a hydrophobic organic solvent in advance, Examples include a method of polymerizing while dripping into a solvent to be contained (pre-dispersion method), a method in which these methods are used in combination, and the reverse of supplying a monomer or an aqueous solution thereof into a solvent containing a hydrophobic organic solvent. A phase suspension polymerization method is preferable, and a method in which a monomer or an aqueous solution thereof is sequentially or continuously fed into a solvent containing a hydrophobic organic solvent under azeotropic conditions is more preferable.

  The polymerization temperature in the polymerization of the monomer is preferably 20 to 120 ° C and more preferably 40 to 100 ° C from the viewpoint of increasing the polymerization rate and obtaining a polymer having good water absorption ability. 0-100 degreeC is preferable and, as for the temperature of a monomer or its aqueous solution, 10-40 degreeC is more preferable.

  In the polymerization of the monomer, various additives can be allowed to coexist in the monomer as long as the polymerization is not adversely affected. Specific examples of such additives include starch-cellulose, starch-cellulose derivatives, polyvinyl alcohol, polyacrylic acid (salt), cross-linked polyacrylic acid (salt), polyethylene glycol, polyvinylpyrrolidone, and the like. Polymerization inhibitors such as auxiliaries and quinones, chain transfer agents, chelating agents and the like.

  The surface of the crosslinked polymer (A) may be further treated with a surface treating agent from the viewpoint of improving liquid permeability.

  Examples of the surface treatment agent include polyvalent metal compounds such as aluminum sulfate, potassium alum, ammonium alum, sodium alum, (poly) aluminum chloride, and hydrates thereof; polycations such as polyethyleneimine, polyvinylamine, and polyallylamine Compound: Silicone compound such as methylsiloxane (also called methicone), dimethylsiloxane (also called dimethicone), polyether-modified silicone, amino-modified silicone; inorganic particles such as silica, alumina, titanium oxide, zinc oxide, bentonite, etc. Only one of these may be used, or two or more may be used in combination.

  Among these, inorganic particles such as silica are preferable in terms of improving the water absorption rate and liquid permeability of the crosslinked polymer.

  The surface treatment of the crosslinked polymer with the surface treating agent may be performed before the crosslinking, at the same time, or after the crosslinking, but is preferably after the crosslinking in order to further exert the effects of the present invention. The method for adding the surface treatment agent is not particularly limited, and dry blending may be used, or an aqueous solution or dispersion may be added. The surface treating agent is preferably used in a proportion of 0.001 to 10% by weight, more preferably 0.01 to 5% by weight, based on the crosslinked polymer.

  The crosslinked polymer (A) produced as described above is polymerized and then subjected to usual post-treatment as necessary, for example, azeotropic dehydration, solvent removal by decantation or centrifugation, vacuum dryer, fluid dryer, etc. The desired polymer can be obtained by performing drying, pulverization treatment, granulation treatment, etc. using the above means.

  The crosslinked polymer (A) can be obtained by the production method as described above, but preferably contains a structural unit derived from an unsaturated carboxylic acid or a salt thereof, and a poly (meth) acrylic acid (salt) -based crosslinked polymer is used. More preferred. In particular, the content of the structural unit derived from (meth) acrylic acid and / or its salt is preferably 50 to 100 mol%, more preferably 70 to 100 mol%, and 90 to 100 mol% of all the structural units. More preferred. The acid group in the polymer is preferably neutralized in an amount of 25 to 100 mol%, more preferably 50 to 99 mol%, and more preferably 55 to 80 mol%. More preferably. Examples of the salt include one or more of alkali metal salts such as sodium, potassium and lithium, ammonium salts, amine salts, ethanolamine salts (including mono-, di-, or tri-forms). . The neutralization of the acid group for forming the salt may be performed in the state of a monomer before polymerization, or may be performed in the state of a polymer during or after polymerization, or may be used in combination. .

[Silicon compound (B)]
The silicon compound (B) used in the present invention is at least one selected from alkoxysilane (1), a hydrolyzate thereof, and a polycondensate thereof.

  The silicon compound (B) does not have a functional group that chemically bonds to the crosslinked polymer (A), and forms a strong skeleton that can withstand impacts such as collisions caused by transportation and transportation.

In the alkoxysilane (1) used in the present invention, R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or a linear or branched chain having 2 to 6 carbon atoms. Although an alkenyl group is shown, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, an isobutyl group, and a t-butyl group. Examples of the alkenyl group include a vinyl group and an allyl group. . Among these, as R ² , an ethyl group is preferable from the viewpoints of safety of by-products generated by hydrolysis, reactivity of hydrolysis reaction, and the like. Moreover, from the point of the physical property of the polysiloxane produced | generated after reaction, 0-2 are preferable for p in General formula (1).

  Preferred examples of the alkoxysilane (1) include tetraethoxysilane, alkyl (alkyl group having 1 to 6 carbon atoms) triethoxysilane, dialkyl (alkyl group having 1 to 6 carbon atoms) diethoxysilane, and the like. Two or more of these alkoxysilanes (1) can be used in combination.

  The alkoxysilane (1) gives a silanol compound (hereinafter referred to as silanol compound (2)) represented by the general formula (2) by hydrolysis.

R ¹ _p Si (OH) _n (OR ² ) _4-pn (2)
[Wherein R ¹ , R ² and p represent the same meaning as described above, and n represents an integer of 1 or more and (4-p) or less. p R ¹ and (4-p−n) R ² may be the same or different. ]
[Water-absorbing crosslinked polymer and production method thereof]
The water-absorbing crosslinked polymer of the present invention contains a crosslinked polymer (A) and a silicon compound (B). The content of the silicon compound (B) in the water-absorbing crosslinked polymer of the present invention is as the content of the alkoxysilane (1) with respect to 100 parts by weight of the crosslinked polymer (A) from the viewpoint of reactivity due to the crosslinking reaction. 1 part by weight or more, particularly 3 parts by weight or more is preferable, 100 parts by weight or less, further 50 parts by weight or less, particularly 30 parts by weight or less are preferable.

The water-absorbing crosslinked polymer of the present invention can be produced by, for example, the methods shown in the following (i) and (ii).
(I) The crosslinked polymer (A) is immersed in a hydrophobic organic solvent, the alkoxysilane (1) and an acid are added, and the alkoxysilane (1) or a hydrolyzate thereof is added to the crosslinked polymer (A). A method of allowing polycondensation after permeation into the gel.
(Ii) When producing a crosslinked polymer (A) by polymerizing a monomer component containing a water-soluble monomer in a hydrophobic organic solvent inert to the polymerization, alkoxysilane (1) and acid during or after the polymerization How to add.

  In the above method, by adding an alkoxysilane (1) and an acid during the production of the crosslinked polymer (A) or the crosslinked polymer (A), the alkoxysilane (1) is hydrolyzed to produce a silanol compound (2 And penetrates into the crosslinked polymer (A). The silanol compound (2) that has penetrated into the cross-linked polymer (A) undergoes polycondensation, so that the cross-linked polymer (A) has a strong skeleton (intercalation polymer network) that can withstand impacts such as collisions caused by transportation and transportation. : IPN), this structure can have good impact resistance, high water absorption and fast diffusivity.

  In the above method, the polycondensation temperature after the alkoxysilane (1) or a hydrolyzate thereof has permeated into the crosslinked polymer (A) is not particularly limited, but is preferably 0 to 120 ° C. Moreover, the addition amount of alkoxysilane (1) is 1 weight part or more with respect to 100 weight part of monomer components which comprise a crosslinked polymer (A) or a crosslinked polymer (A) from a viewpoint of obtaining favorable impact resistance. 3 parts by weight or more is more preferable, 100 parts by weight or less is preferable, 50 parts by weight or less is more preferable, and 30 parts by weight or less is still more preferable.

  In the above method, examples of the hydrophobic organic solvent include the hydrophobic organic solvents described in the above-mentioned column of [Crosslinked Polymer (A)].

  The acid used in the above method serves as a catalyst for hydrolysis reaction and polycondensation reaction of alkoxysilane (1), and may be an organic acid or an inorganic acid. As the acid, an organic acid or an inorganic acid having a first dissociation index (pKa1) in the range of −10 to 5 is preferable.

  Specific examples of acids include inorganic acids such as hydrochloric acid (pKa = -8), sulfuric acid (pKa = 1.99), phosphoric acid (pKa = 2.15, 7.20, 12.35); oxalic acid (pKa = 1.04, 3.82), maleic acid (PKa = 1.75, 5.83), tartaric acid (pKa = 2.82, 3.96), fumaric acid (pKa = 2.85, 4.10), citric acid (pKa = 2.90, 4.34), malic acid (pKa = 3.24, 4.71), succinic acid ( Organic acids such as pKa = 4.00, 5.24), formic acid (pKa = 3.55), lactic acid (pKa = 3.66), adipic acid (pKa = 4.26, 5.03), acetic acid (pKa = 4.56), propionic acid (pKa = 4.67) An organic acid having a first dissociation constant (pKa1) in the range of 2.9 to 5.0, particularly 3.5 to 5.0 is preferable from the viewpoint of easy pH adjustment.

  The amount of the acid is preferably 0.001 to 10% by weight, more preferably 0.001 to 5% by weight, based on the alkoxysilane (1) from the viewpoint of suppressing the condensation reaction of the alkoxysilane (1).

  In the above method, when the alkoxysilane (1) and the acid are added, it is preferably added as a solution of water or a water-soluble organic solvent (hereinafter referred to as an additive solution). The concentration of alkoxysilane (1) in the added solution is preferably 5 to 95% by weight, more preferably 10 to 80% by weight, and still more preferably 20 to 70% by weight, from the viewpoint of controlling the condensation reaction.

  The water-soluble organic solvent used in the additive solution is preferably one that dissolves uniformly when mixed with the alkoxysilane (1), such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, Examples include propylene glycol, ethylene glycol monoethyl ether, acetone, diethyl ether, tetrahydrofuran, diacetone alcohol and the like.

  The additive solution preferably contains a surfactant in order to promote good dispersibility of the alkoxysilane (1) and the hydrolysis reaction of the alkoxysilane (1). As the surfactant, any of a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant can be used.

  Nonionic surfactants include polyoxyalkylene alkyl ether, polyoxyalkylene alkenyl ether, higher fatty acid sucrose ester, polyglycerin fatty acid ester, higher fatty acid mono- or diethanolamide, polyoxyethylene hydrogenated castor oil, polyoxyethylene sorbitan fatty acid Examples thereof include esters, polyoxyethylene sorbite fatty acid esters, alkyl saccharide surfactants, alkyl amine oxides, and alkyl amido amine oxides. Of these, polyoxyalkylene alkyl ether and polyoxyethylene hydrogenated castor oil are preferable, and polyoxyethylene alkyl ether is particularly preferable.

  Anionic surfactants include alkyl benzene sulfonate, alkyl or alkenyl ether sulfate, alkyl or alkenyl sulfate, olefin sulfonate, alkane sulfonate, saturated or unsaturated fatty acid salt, alkyl or alkenyl ether carboxylate , Α-sulfone fatty acid salt, N-acylamino acid type surfactant, phosphoric acid mono- or diester type surfactant, sulfosuccinic acid ester and the like. Counter ions of the anionic surfactant include alkali metal ions such as sodium ions and potassium ions; alkaline earth metal ions such as calcium ions and magnesium ions; ammonium ions; alkanol groups having 2 or 3 carbon atoms are 1-3 Examples thereof include alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, and triisopropanolamine.

  Examples of the cationic surfactant include a quaternary ammonium salt type surfactant, and a mono long chain alkyl (alkyl group having 16 to 24 carbon atoms) type quaternary ammonium salt is preferable. Specific examples include cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, aralkyltrimethylammonium chloride, and behenyltrimethylammonium chloride. Stearyltrimethylammonium chloride and behenyltrimethylammonium chloride are particularly preferable.

  Examples of amphoteric surfactants include imidazoline series, carbobetaine series, amide betaine series, sulfobetaine series, hydroxysulfobetaine series, and amide sulfobetaine series.

  Among these surfactants, from the viewpoint of obtaining good dispersibility, nonionic surfactants of HLB 9 to 15, particularly 11 to 14 are preferred. In addition, HLB here shows the calculated value by the Griffin method.

  Surfactants can also be used in combination of two or more, and the addition amount of the surfactant is 0.01 to from the viewpoint of emulsification during mixing and acceleration of hydrolysis to the alkoxysilane (1). 25 weight% is preferable and 0.1-10 weight% is more preferable.

  In the method (i), water may be present. Although there is no restriction | limiting in particular in the quantity of water, 0-120 weight part is preferable with respect to 100 weight part of a crosslinked polymer (A).

  In the method (ii), the alkoxysilane (1) and the acid may be added at a time when the monomer component is charged in an amount of 0 to 100% of the total monomer amount. It is preferable to add between 50 and 100%. Further, when the alkoxysilane (1) and the acid are added before the crosslinking agent is added, the IPN structure by hydrolysis and polycondensation of the alkoxysila (1) is converted into a crosslinked polymer (1) before the crosslinked structure is formed. A) is preferable because it can be built up to the inside.

  The shape of the water-absorbing crosslinked polymer of the present invention is not particularly limited, and examples thereof include a sheet shape and a particle shape, but a particle shape is preferable.

The water-absorbing crosslinked polymer of the present invention is further classified, for example, from the viewpoint of obtaining excellent liquid permeability, water absorption, water absorption speed, and from the viewpoint of not causing discomfort when touching the human body in actual use situations. For example, the average particle size is preferably adjusted to 1 to 5000 μm, more preferably 100 to 1000 μm, even more preferably 200 to 550 μm, and particularly preferably 270 to 420 μm.
In addition, the average particle diameter of the water-absorbing crosslinked polymer of the present invention is a value measured by the method shown in the examples.

The bulk specific gravity of the water-absorbent crosslinked polymer of the present invention is preferably in the range of 0.1 to 0.9 g / mL, from the viewpoint of obtaining excellent liquid permeability, water absorption, and water absorption speed, and 0.30 to 0.88 g. The range of / mL is more preferable.
The bulk specific gravity of the water-absorbent crosslinked polymer of the present invention is a value measured by the method shown in the examples.

The water absorption amount of the water-absorbing crosslinked polymer of the present invention is 20 g / g or more from the viewpoint of suppressing the use amount of the water-absorbing crosslinked polymer per absorber such as diapers, for example, suppressing the diapers and the like from becoming thick. Preferably, 25 g / g or more is more preferable.
The water absorption of the water-absorbing crosslinked polymer of the present invention is a value measured by the method shown in the examples.

The water absorption rate of the water-absorbent crosslinked polymer of the present invention is preferably 10 mL / min or more, more preferably 15 mL / min or more, still more preferably 20 mL / min or more, from the viewpoint of quickly absorbing urine and preventing leakage. 30 mL / min or more is even more preferable.
The water absorption rate of the water-absorbing crosslinked polymer of the present invention is a value measured by the method shown in the examples.

  From the viewpoint of preventing leakage by suppressing the gel blocking (clogging of gel particles) caused by the swollen water-absorbing crosslinked polymer, the liquid-absorbing cross-linking speed of the water-absorbing crosslinked polymer of the present invention is quickly diffused. 40 mL / min or more is preferable, 60 mL / min or more is more preferable, and 70 mL / min or more is still more preferable.

  In addition, the water-absorbing crosslinked polymer of the present invention is not subjected to a significant decrease in the liquid passing speed due to impacts such as collisions caused by transportation and transportation, and in order to obtain good impact resistance, the lab shown in the following examples The amount of water absorption after the impact experiment is preferably 20 g / g or more, more preferably 25 g / g or more, and the water absorption rate is preferably 10 mL / min or more, more preferably 15 mL / min, further preferably 20 mL / min or more. It is desirable that the liquid passing rate under pressure is preferably 40 mL / min or more.

  The water-absorbing crosslinked polymer of the present invention has an average particle size of 1 to 5000 μm, a bulk specific gravity of 0.1 to 0.9 g / mL, a water absorption amount (with respect to physiological saline) of 20 g / g or more, and a water absorption rate of 10 mL / mL. By maintaining the five physical properties in a well-balanced manner such that the liquid passing rate under pressure (with respect to physiological saline) is 40 mL / min or more for a minute or more, the effect as the water-absorbent resin particles can be sufficiently exhibited. Furthermore, impact such as collision caused by transportation / transport of the water-absorbing crosslinked polymer can be reduced, and good impact resistance can be obtained.

  Therefore, the water-absorbent crosslinked polymer of the present invention is an absorbent for hygiene articles such as disposable diapers for infants, adults or incontinent (disposable diapers) or sanitary napkins for women, a water-absorbing agent for simple toilets, It is suitably used for applications such as a solidifying agent for waste liquids and a water retention agent for agriculture, and can be suitably used as a highly water-absorbing resin contained in an absorbent material for sanitary materials such as diapers.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the examples, “%” and “parts” are “% by weight” and “parts by weight” unless otherwise specified.

  In addition, the measuring method of the physical property performed in the Example and the comparative example is as follows.

-Measuring method of average particle diameter 100g of polymer particles were classified using the sieve based on JISZ-8801-1982, and the average particle diameter was calculated | required from the weight fraction of each fraction.

-Measurement method of bulk specific gravity The loose bulk specific gravity of the polymer particles was determined using a casa specific gravity measuring instrument (JIS K-3362) manufactured by Tsutsui Rika Instruments Co., Ltd.

Measurement method of water absorption After 1 g of polymer particles were swelled with 150 mL of physiological saline (0.9% NaCl aqueous solution, manufactured by Otsuka Pharmaceutical Co., Ltd.) for 30 minutes, they were placed in a 250 mesh non-woven bag and 143 G with a centrifuge. Dehydrate for 10 minutes and measure the total weight (total weight) after dehydration. Then, the retained amount after centrifugal dehydration is measured according to the following equation (3).

Here, the remaining amount of nonwoven fabric bag liquid = (weight of nonwoven fabric after centrifugal dehydration) − (weight of nonwoven fabric bag).
The water absorption was measured for the polymer particles before and after the following laboratory impact experiment.

・ Measurement method of water absorption speed In a 100 mL glass beaker, 50 mL of physiological saline (0.9 wt% sodium chloride water) and a magnetic stirrer chip (center diameter 8 mm, both ends diameter 7 mm, length 30 mm, surface is fluorine) The resin beaker is placed, and the beaker is placed on a magnetic stirrer (HPS-100 manufactured by ASONE). The rotational speed of the magnetic stirrer is adjusted to 600 ± 5 rpm, and the physiological saline is stirred. 2.0 g of polymer particles as a measurement sample are put into the liquid at the center of the vortex of the saline solution being stirred, and the water absorption rate (seconds) of the polymer particles is determined according to JIS K 7224 (1996). taking measurement. Specifically, the stopwatch is started when the introduction of polymer particles into the beaker is completed, and stopped when the stirrer tip is covered with the test liquid (when the vortex disappears and the liquid surface becomes flat). Stop the watch and measure the time T (seconds). Recorded as the rate of water absorption by the vortex method (= 1500 / T (mL / min)). In the measurement, n = 5 was measured, the values at each of the upper and lower points were deleted, and the average value of the remaining three points was taken as the measured value. These measurements are performed at 23 ± 2 ° C. and humidity 50 ± 5%, and are measured after storing the materials in the same environment for 24 hours or more before the measurement.
The water absorption rate was measured on polymer particles before and after the following laboratory impact experiment.

・ Measurement method of liquid flow rate under pressure In a 100 mL glass beaker, a sufficient amount of physiological saline (0.9 wt% sodium chloride water) to swell polymer particles 0.32 ± 0.005 g as a measurement sample For example, it is immersed in a physiological saline 5 times or more of the saturated absorption amount of the polymer particles and left for 30 minutes.

Separately, a narrow tube (inner diameter 4 mm, length) with a filter (inner diameter 80 to 100 μm, biocolumn sintered stainless steel filter) and a cock (inner diameter 2 mm) at the lower end of a vertically standing cylinder (inner diameter 25.4 mm). 8 cm), and the contents of the beaker including the swollen measurement sample are put into the cylindrical tube with the cock closed. Open the cock and adjust the liquid level in the filtration cylinder to 5 cm above the 60 mL scale line. Next, a cylindrical rod having a diameter of 2 mm with a wire mesh having an opening of 150 μm and a diameter of 25 mm is inserted into the filtration cylindrical tube so that the wire mesh and the measurement sample are in contact with each other. Place a weight so that the load of. After standing in this state for 1 minute, the cock is opened to allow the liquid to flow, and the time until the liquid level in the filtration cylindrical tube reaches the 40 mL scale line from the 60 mL scale line (that is, 20 mL of liquid passes) (T ₁ ) (Seconds) is measured with a stopwatch. Using the measured time T ₁ (seconds), the flow rate at 2.0 kPa is calculated from the following equation. In the equation, T ₀ (seconds) is a value obtained by measuring the time required for 20 mL of physiological saline to pass through the wire mesh without putting a measurement sample in the filtration cylindrical tube.

Flow rate (mL / min) = 20 × 60 / (T ₁ −T ₀ )
The value obtained by the above formula is divided by the thickness of the swollen polymer particle layer in the cylinder, and converted to a value per 20 mm to obtain a liquid passing rate under pressure. The measurement was performed 5 times (n = 5), the values at each of the upper and lower points were deleted, and the average value of the remaining three points was taken as the measured value.
In addition, the measurement of the liquid flow rate under pressure was performed on the polymer particles before and after the following laboratory impact experiment.

<Lab impact experiment>
In a 50 mL screw tube, 5.00 g of polymer particles as measurement samples and 12 10 mm zirconia beads (about 47 g) were placed, the lid was closed, and the sample was placed on a desktop bead mill (V-1 type) manufactured by Irie Shokai. . After impacting the polymer particles by a bead mill treatment for 5 minutes, the polymer particles were taken out and used as polymer particles after a laboratory impact experiment.

Example 1
Kao Co., Ltd. Emar 20C (Polyoxyethylene (EO average addition mole) as a dispersant in a SUS304 5L reaction vessel (using anchor blades) equipped with a stirrer, reflux condenser, monomer dropping port, nitrogen gas inlet tube, thermometer Formula 3) 0.1% [weight of acrylic acid] of alkyl (C12) ether sulfate ester Na) was charged, and 1600 mL of polymerization solvent cyclohexane was added. Nitrogen gas was blown for the purpose of expelling dissolved oxygen, the anchor blade was stirred at 300 r / min, and the internal temperature was raised to 76 ° C.

  Meanwhile, in a 2 L three-necked flask, 506.2 g of 80% acrylic acid manufactured by Toagosei Co., Ltd. and 216.5 g of ion exchange water were charged, and 330.8 g of 48% caustic soda aqueous solution manufactured by Asahi Glass Co., Ltd. was cooled with ice. The solution was added dropwise to obtain 1053.5 g of a sodium acrylate aqueous solution as a monomer aqueous solution. To this aqueous monomer solution, 0.175 g of N-acylated glutamic acid sodium (Ajinomoto Healthy Supply Co., Ltd., trade name Amisoft GS-11F) dissolved in 3.13 g of ion-exchanged water was added and stirred for a while. It was divided into 264 g, 264 g, and 528 g.

  Next, 0.1224 g of 2,2′-azobis (2-amidinopropane) dihydrochloride (trade name V-50) manufactured by Wako Pure Chemical Industries, Ltd., 0.204 g of polyethylene glycol (PEG 6000) manufactured by Kao Corporation, ion 14.0 g of exchange water was mixed and dissolved to prepare an initiator (A) aqueous solution. Moreover, Wako Pure Chemical Industries Ltd. sodium persulfate 0.49g was melt | dissolved in ion-exchange water 10.4g, and initiator (B) aqueous solution was prepared. Furthermore, a titanium citrate aqueous solution (citric acid / Ti molar ratio 2.0, Ti amount 0.03% [to acrylic acid]) was prepared.

  A solution was prepared by mixing 1.5 g of adipic acid (manufactured by Sigma Aldrich Japan Co., Ltd.), 138.5 g of ion exchange water, and 10 g of polyoxyethylene lauryl ether (Emulgen 108 manufactured by Kao Corporation) (acid solution (A )). 50 g of methyltriethoxysilane (MTEOS manufactured by Tokyo Chemical Industry Co., Ltd.) and 150 g of acid solution (A) were vigorously mixed to obtain a uniform solution (hereinafter referred to as MTEOS solution (A)).

  7.16 g of the aqueous initiator (A) solution was added to one of the three aqueous monomer solutions (264 g) (monomer (1)). Moreover, 7.16 g of initiator (A) aqueous solution and 1.57 g of titanium citrate aqueous solution were added to another monomer aqueous solution (264 g) divided into three (monomer (2)). To the remaining aqueous monomer solution (528 g), the initiator (B) aqueous solution 10.88 g and the titanium citrate aqueous solution 3.15 g were added (monomer (3)).

  After confirming that the internal temperature of the 5 L reaction vessel was 77 ° C., the monomer (1) was dropped from the monomer dropping port using a microtube pump over 15 minutes for polymerization. Subsequently, the monomer (2) was added dropwise over 15 minutes for polymerization. Subsequently, the monomer (3) was dropped and polymerized. On the 20th minute after the monomer (3) was added dropwise, 200 g of the above-mentioned MTEOS solution (A) was added, and the solution was dropped and polymerized at the same pace. Polymerization was completed in 30 minutes after the monomer (3) was dropped.

  After completion of the polymerization, azeotropic dehydration was performed using a dehydrating tube, and the water content of the polymer particles was adjusted to 60 parts with respect to 100 parts of the polymer particles. Then, what melt | dissolved 0.326 g of ethylene glycol diglycidyl ether (brand name Denacol EX-810) by Nagase Chemical Industries Ltd. in 10.0 g of water was added as a crosslinking agent. Thereafter, azeotropic dehydration was further performed to adjust the water content of the polymer particles to 40 parts with respect to 100 parts of the polymer particles. After cooling, the heptane was removed by decantation, and the polymer particles were obtained by drying under conditions of 130 ° C. and about 6.7 kPa for 14 hours.

  Surface treatment was performed by dry blending 0.5 part of Aerosil 200 manufactured by Nippon Aerosil Co., Ltd. with respect to 100 parts of the polymer particles to obtain water-absorbing crosslinked polymer particles.

Example 2
In Example 1, instead of the MTEOS solution (A), 50 g of tetraethoxysilane (TEOS manufactured by Shin-Etsu Chemical Co., Ltd.), 50 g of 0.1N hydrochloric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.), polyoxyethylene lauryl A uniform solution of 10 g of ether (Emulgen 108 manufactured by Kao Corporation) was prepared (TEOS solution).

  Then, in Example 1, instead of adding the monomer (3) dropwise and adding 200 g of the MTEOS solution (A) 20 minutes later, the monomer (3) is dropped and the TEOS solution 110 g is added 25 minutes later Produced water-absorbing crosslinked polymer particles in the same manner as in Example 1.

Example 3
In Example 1, instead of the MTEOS (A) solution, 150 g of tetraethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 150 g of 0.1N hydrochloric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.), polyoxyethylene lauryl ether A uniform solution of 30 g (Emalgen 108 manufactured by Kao Corporation) was prepared (TEOS solution).

  Then, in Example 1, instead of adding the monomer (3) dropwise and adding 200 g of the MTEOS solution (A) at 20 minutes, the monomer (3) was dropped and the TEOS solution 330 g was added at the 20th minute. Produced water-absorbing crosslinked polymer particles in the same manner as in Example 1.

Example 4
In Example 1, instead of the MTEOS solution (A), 25 g of tetraethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 25 g of 0.1N hydrochloric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.), polyoxyethylene lauryl ether A uniform solution of 5 g (Emalgen 108 manufactured by Kao Corporation) was prepared (TEOS solution).

  In Example 1, instead of adding 200 g of the MTEOS solution (A) 20 minutes after dropping the monomer (3), the monomer (3) is dropped and 55 g of the TEOS solution is added at 25 minutes. Produced water-absorbing crosslinked polymer particles in the same manner as in Example 1.

Example 5
In Example 1, instead of the MTEOS solution (A), a uniform solution of 61.1 g of the same acid solution (A) as in Example 1 and 75.0 g of methyltriethoxysilane (MTEOS manufactured by Tokyo Chemical Industry Co., Ltd.) Then, 25.0 g of diethoxydimethylsilane (DMDEOS manufactured by Shin-Etsu Chemical Co., Ltd.) was added and dissolved to prepare a solution (hereinafter referred to as MTEOS solution (B)).

  Then, in Example 1, instead of adding 200 g of the MTEOS solution (A) 20 minutes after dropping the monomer (3), the MTEOS solution (B) 161 was dropped 27 minutes after the monomer (3) was dropped. Except for adding 0.1 g, water-absorbing crosslinked polymer particles were obtained in the same manner as in Example 1.

Comparative Example 1
In Example 1, water-absorbing crosslinked polymer particles were obtained in the same manner as in Example 1 except that only the monomer (3) was added dropwise over 30 minutes for polymerization without adding the MTEOS solution (A).

Comparative Example 2
In Example 4, water-absorbing polymer particles were obtained in the same manner as in Example 4 except that no crosslinking agent was added after completion of the polymerization.

Example 6
A uniform solution of 5 g of tetraethoxysilane (TEOS manufactured by Shin-Etsu Chemical Co., Ltd.), 5 g of 0.01N hydrochloric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.), and 1 g of polyoxyethylene lauryl ether (Emulgen 108 manufactured by Kao Corporation) Was prepared (TEOS solution).

  10 g of the water-absorbing crosslinked polymer particles (no added aerosil) obtained in the same manner as in Comparative Example 1 was placed in a 50 mL container, and 20 mL of normal heptane was poured and stirred. Next, 4.4 g of the TEOS solution was added dropwise. After 1 minute, normal heptane was removed by decantation, and dried under conditions of 130 ° C., about 6.7 kPa for 14 hours to obtain water-absorbing crosslinked polymer particles.

Example 7
A solution was prepared by mixing 1.5 g of adipic acid (manufactured by Sigma Aldrich Japan Co., Ltd.), 138.5 g of ion exchange water, and 10 g of polyoxyethylene lauryl ether (Emulgen 108 manufactured by Kao Corporation) (acid solution (A )). 5 g of methyltriethoxysilane (MTEOS manufactured by Tokyo Chemical Industry Co., Ltd.) and 15 g of acid solution (A) were vigorously mixed to obtain a uniform solution (hereinafter referred to as MTEOS solution).

  10 g of the water-absorbing crosslinked polymer particles (no added aerosil) obtained in the same manner as in Comparative Example 1 was placed in a 50 mL container, and 20 mL of normal heptane was poured and stirred. Next, 12 g of the MTEOS solution was added dropwise. After 1 minute, normal heptane was removed by decantation, and dried under conditions of 130 ° C., about 6.7 kPa for 14 hours to obtain water-absorbing crosslinked polymer particles.

  For the polymer particles obtained in Examples 1 to 7 and Comparative Examples 1 and 2, the average particle size and bulk specific gravity, the amount of water absorption before and after the laboratory impact experiment, the water absorption speed, and the liquid passing speed under pressure were evaluated. These results are shown in Table 1.

Claims (7)

A crosslinked polymer (A) obtained by polymerizing a monomer component containing a water-soluble monomer, and a general formula (1)
R ¹ _p Si (OR ² ) _4-p (1)
[Wherein, R ¹ and R ² each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms or a linear or branched alkenyl group having 2 to 6 carbon atoms, and p R ¹ and (4-p) R ² may be the same or different. p shows the integer of 0-3. ]
A water-absorbing crosslinked polymer containing at least one silicon compound (B) selected from the group consisting of alkoxysilanes (hereinafter referred to as alkoxysilanes (1)), hydrolysates thereof, and polycondensates thereof.   The water-absorbing crosslinked polymer according to claim 1, wherein the crosslinked polymer (A) contains a structural unit derived from an unsaturated carboxylic acid or a salt thereof.   The water-absorbent crosslinked polymer according to claim 1 or 2, wherein the water absorption amount (with respect to physiological saline) is 20 g / g or more and the water absorption rate (with respect to physiological saline) is 10 mL / min or more.   The average particle size is 1 to 5000 μm, the bulk specific gravity is 0.1 to 0.9 g / mL, the water absorption (to physiological saline) is 20 g / g or more, and the water absorption rate (to physiological saline) is 10 mL / min or more. The water-absorbent crosslinked polymer according to any one of claims 1 to 3, which is a polymer particle having a rolling reduction rate (to physiological saline) of 40 mL / min or more.   The crosslinked polymer (A) is immersed in a hydrophobic organic solvent, the alkoxysilane (1) and an acid are added, and the alkoxysilane (1) or a hydrolyzate thereof is infiltrated into the crosslinked polymer (A). The method for producing a water-absorbent crosslinked polymer according to any one of claims 1 to 4, wherein the polycondensation is carried out thereafter.   When producing a crosslinked polymer (A) by polymerizing a monomer component containing a water-soluble monomer in a hydrophobic organic solvent inert to the polymerization, an alkoxysilane (1) and an acid are added during or after the polymerization. The manufacturing method of the water absorptive crosslinked polymer in any one of Claims 1-4.   The method for producing a water-absorbent crosslinked polymer according to claim 5 or 6, wherein the acid is an organic acid or an inorganic acid having a first dissociation index (pKa1) in the range of -10 to 5.